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The
Great Barrier Reef, a chain of coral
reefs in the Coral
Sea, off the northeastern coast of Australia.
The largest deposit of coral in the world, the reef extends about 2,010 km
(about 1,250 mi) from a point near Mackay, Queensland, to the Torres
Strait, which lies between Australia and New Guinea.
The channel that separates the
reef from the Australian coast varies in width. Certain northern parts of the
reef are as close as 16 km (10 mi) to the coast. In the south, the channel
reaches a width of about 240 km (about 150 mi). The reef protects the channel
from the harsh wind and waves of the Coral Sea. Water in the channel is calm and
shallow. Islets and rings of coral called atolls are scattered throughout
the channel, making ship navigation difficult.
The Great Barrier Reef is home
to a remarkable number of organisms. The coral itself is made up of the
skeletons of tiny, flowerlike water animals called polyps, held together
by a limestone substance produced by a type of algae. Hundreds of species of
polyps form coral in a beautiful range of colors and shapes. The reef also
supports many larger water animals, including as many as 2000 species of fish.
Since the early 1960s
crown-of-thorns starfish have invaded parts of the reef. These animals feed on
coral and can destroy large portions of a coral reef. The Australian government
has made efforts to limit destruction of the coral.
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